Dental floss is defined in Webster's New World Dictionary, 1983, as “ . . . thread for removing food particles between the teeth.”
The concept of using dental floss for cleansing interproximal spaces appears to have been introduced by Parmly in 1819, Practical Guide to the Management of Teeth, Cullins & Croft Philadelphia, Pa. Numerous types of floss were developed and used for cleaning interproximal and subgingival surfaces, until finally in 1948 Bass established the optimum characteristics of dental floss, Dental Items of Interest, 70, 921–34 (1948).
Bass cautioned that dental floss treated with sizing, binders and/or wax produces a “cord” effect as distinguished from the desired “spread filament effect”. This cord effect reduces flossing efficiency dramatically and visually eliminates splaying (i.e., the flattening and spreading out of filaments) necessary to achieve the required interproximal and subgingival mechanical cleaning. This cleaning is then required to be followed by the entrapment and removal of debris, plaque and microscopic materials from interproximal spaces by the “spread” floss as it is removed from between teeth.
Proper use of dental floss is necessary to clean the considerable surface area on the interproximal surfaces of teeth, which cannot usually be reached by other cleaning methods or agents, e.g., the bristles of a toothbrush, the swishing action of a rinse, or by the pulsating stream from an oral irrigator.
Historically, the purpose of dental floss was to:                (1) dislodge and remove any decomposing food material, debris, etc., that has accumulated at the interproximal surfaces, which could not be removed by other oral hygiene means, and        (2) dislodge and remove as much as possible the growth of bacterial material (plaque, tartar, calculus) that had accumulated there since the previous cleaning.        
Effective oral hygiene requires that three control elements be maintained by the individual:                (1) Physical removal of stains, plaque and tartar. This is accomplished in the strongest sense by scraping and abrasion in the dentist's office. Self administered procedures are required frequently between visits and range from tooth brushing with an appropriate abrasive toothpaste through flossing and water jet action down to certain abrasive foods and even the action of the tongue against tooth surfaces.        (2) Surfactant Cleaning. This is required to remove: food debris and staining substances before they adhere to the tooth surface; normal dead cellular (epithelial) material which is continually sloughed off from the surfaces of the oral cavity and microbial degradation products derived from all of the above. Besides the obvious hygienic and health benefits related to simple cleanliness provided by surfactants, there is an important cosmetic and sense-of-well-being benefit provided by surfactant cleansing. Research has shown that the primary source of bad breath is the retention and subsequent degradation of dead cellular material sloughed off continuously by the normal, healthy mouth.        (3) Frequency of Cleansing. This is perhaps the most difficult to provide in today's fast-paced work and social environment. Most people recognize that their teeth should be brushed at least 3 times a day and flossed at least once a day. The simple fact is that most of the population brush once a day, some brush morning and evening, but precious few carry toothbrush and dentifrice to use the other three or four times a day for optimal oral hygiene. Consumer research suggests that the population brushes an average of 1.3 times a day. Most surprising, less than 15% of adults floss regularly. Reasons offered for not flossing: difficult to do, painful, not effective, doesn't seem to do anything, and leaves a bad taste.        
Most commercial interproximal devices marketed at the present time contain various coatings of wax or wax like substances that function as: binders for the various multifilament flosses to minimize fraying, lubricants, flavor carriers, and/or fluoride carriers. When added to various monofilament dental tapes, generally at substantially lower levels, wax functions as a lubricant and/or flavor/active ingredient carrier.
An almost universal shortcoming common to most waxed dental flosses and to all coated monofilament dental tapes is the user perception during flossing that the dental floss or dental tape is “not working” and/or “not cleaning”, etc.
In fact, most of these devices have only marginal efficacy with respect to removing biofilms (plaque). Biofilms generally require physical abrasive-type action to be effectively removed. Periodic professional cleaning is a recommended means for effectively controlling biofilm formation.
The classification of plaque as a biofilm is considered a major advance in the development of more effective “self-treatment” oral care products. See the following biofilm references:
Greenstein and Polson, J. Periodontol., May 1998, 69:5:507–520; van Winkelhoff, et al., J. Clin. Periodontol., 1989, 16:128–131; and Wilson, J. Med. Microbiol., 1996, 44:79–87.                Biofilms are defined as “ . . . matrix-enclosed bacterial population adherent to each other and to the surface or intersurfaces. These masses secrete an exopolysaccharide matrix for protection. Considerably higher concentrations of drugs are needed to kill bacteria in biofilms than organisms in aqueous suspensions.”        
Costerton, J. W., Lewandowski, Z., DeBeer, D., Caldwell, D., Korber, D., James, G. Biofilms, the customized microniche. J. Bacterio., 1994, 176:2137–2142.                The unique attributes of biofilms is being recognized as increasingly important in the 1990's. Future studies into the mode of growth of biofilms will allow manipulation of the bacterial distribution.        
Douglass, C. W., Fox, C. H. Cross-sectional studies in periodontal disease: Current status and implications for dental practice. Adv. Dent. Res., 1993, 7:26–31.                The number of adults over 55 who will need periodontal services will increase. The type of services will need to be adjusted to meet the need.        
Greenstein, G. J., Periodontal response to mechanical non-surgical therapy: A review. Periodontol., 1992, 63:118–130.                Mechanical therapy remains effective with caveats of compliance and skill of therapists.        
Marsh, P. D., Bradshaw, D. J. Physiological approaches to the control of oral biofilms. Adv. Dent. Res., 1997, 11:176–185.                Most laboratory and clinical findings support the concept of physiological control.        Further studies will reveal details of biofilm diversity.        
Page, R. C., Offenbacher, S., Shroeder, H., Seymour, G. J., Kornman, K. S. Advances in the pathogenesis of periodontitis: Summary of developments, clinical implications and future directions. Periodont. 2000, 1997, 14:216–248.                Genetic susceptibility to three oral anaerobic bacteria play an important part in the progression of periodontitis. Acquired and environmental risk factors exacerbate the problem. Mechanical disruption will remain an effective and essential part of periodontal therapy.        Papapanou, P. N., Engebretson, S. P., Lamster, I. B. Current and future approaches for diagnosis of periodontal disease. NY State Dent. J., 1999, 32–39.        New techniques are available such as a novel pocket depth measurement device, microscopic techniques, immunoassay, DNA probes, BANA hydrolysis tests. These more clearly define the nature of periodontitis.        